They came in some numbers to watch the South Africa opening batsman make his debut for his new county. And a few were not disappointed. However it was Alviro Petersen, now of Somerset, not Graeme Smith of Surrey, who grabbed the attention.

Petersen batted at No3, which allowed Nick Compton the chance of playing against the new ball by giving him the opening berth alongside Marcus Trescothick. Compton, who has usually batted at three for Somerset, could not gain much more experience. After his departure for a duck, dragging a full-length delivery from Jade Dernbach on to his stumps, Petersen hit the most serene of centuries. He scored swiftly but he never seemed to be in a hurry. His innings of 167 from 255 balls, which came to an end 15 minutes before the close, was a superb start to his Somerset career.

Petersen had a bit of help. Stuart Meaker unwittingly attacked the leg stump – just where Petersen likes them – and he put the ball away unerringly to the leg-side boundaries. Against the spinners – Surrey opted for two on a slow and surprisingly brown pitch – he occasionally popped down the pitch to hit the ball over the infield. Otherwise he punctured the gaps on the leg-side at will. Smith, standing massively at slip, must know Petersen's game intimately but in this case knowledge did not equal power.

It was a benign surface for batting but only Petersen ever suggested permanence. Compton, after a few impeccable leaves, soon became one of four victims for Dernbach, who was, by a huge margin, the most dangerous of Surrey's bowlers. Trescothick was deceived by the first ball he received from Gareth Batty; James Hildreth dragged on against Dernbach straight after lunch.

Craig Kieswetter was Petersen's most trustworthy ally in a 143-run partnership until he was beaten by Batty, who passed his outside edge by virtue of shrewdly bowling around the wicket. Jos Buttler could not last as long. Indeed, there was a flurry of activity when Surrey took the second new ball. Buttler shouldered arms to Dernbach's first delivery with the new ball and watched his off-stump being disturbed; Peter Trego nibbled at the next one and was caught at second slip and suddenly Somerset's ascendancy was gone.

Alfonso Thomas only just managed to prevent a hat-trick. Few were convinced that he had left Dernbach's next delivery intentionally.

Thereafter Surrey took charge. Petersen was lbw to Zander de Bruyn and Meaker's day improved when he yorked Jamie Overton, more than six and a half feet tall and susceptible. However, Dernbach's success helped to conceal the odd, lop-sided nature of Surrey's side. They played just two frontline pacemen, who were augmented by De Bruyn, and two spinners – like Smith and Vikram Solanki, Gary Keedy made his Surrey debut, a trio that rack up 107 years between them. Thus Surrey had the insurance of seven batsmen but limited options for Smith in the field. Presumably this was his idea. Not many people tell Smith what to do.

Moreover, Surrey preferred Meaker, who had a forgettable day, to Chris Tremlett, which was also something of a surprise. Tremlett was bowling in the warm-ups before the game; it was confirmed that he was fit but they chose not to play him. It is impossible to imagine any other county omitting a fit Tremlett. It seems as if England rate him rather more highly than Surrey.